Support mesoporosity: a tool for better control of catalytic behavior of cobalt supported Fischer Tropsch catalysts

Influence of support porous structure on Fischer-Tropsch reaction rates and selectivities was studied over cobalt supported catalysts with a wide range of cobalt contents (5-50 wt %). Periodic (SBA-15 and MCM-41) and commercial mesoporous silicas were used as catalytic supports. A combination of characterization techniques (adsorption, XRD, and TGA) showed that the sizes of supported cobalt particles and cobalt reducibility strongly depended on pore diameters of mesoporous silicas: small pore diameters led to smaller sizes of supported Co clusters and their lower reducibility in hydrogen. The catalytic measurements in a fixed bed reactor at total pressures of 1-20 bar showed that the catalytic behavior of silica supported Co catalysts over the wide range of cobalt contents was primarily governed by catalyst porous structure. The reaction rate and C5+ selectivity increased with increasing catalyst pore diameters. The results suggest that the support mesoporosity provides an efficient tool for the design of Fischer-Tropsch catalysts with desired catalytic properties.